1. Field of the Invention
The present invention relates to a resin granulating apparatus provided in a mixer or an extruder.
2. Description of the Related Art
A resin granulating apparatus for producing a pellet of resin is to granulate the resin by cutting molten resin extruded from a die into water by a rotating cutter. This cutter is rotated while pressed from the normal direction relative to a die surface. When a blade of the cutter is in close contact with the die surface without any gap therebetween, the material is cut into a pellet of a best shape. However, abrasion is easily generated in the blade of the cutter, and in accordance with progress of the abrasion, the gap between the cutter and the die surface tends to be increased. The blade of the cutter may be strongly pressed onto the die surface so as to bring the blade of the cutter into close contact with the die surface without any gap therebetween. However, there is a fear that with excessive pressing force, the abrasion of the cutter is accelerated so as to shorten the life of the cutter.
Therefore, a conventional resin granulating apparatus is provided with stopper means for pressing the cutter onto the die surface and regulating the blade of the cutter not to come close to the die surface more than necessary. For example, Japanese Patent Laid-Open No. 1994-297451 discloses stopper means provided on a cutter shaft on the side of the die relative to a sleeve for retaining the cutter shaft for rotating the cutter through bearings. This stopper means is provided with a spinning disc and a nut disc both of which are rotatably attached to the cutter shaft. The nut disc is moved relatively to the spinning disc so as to adjust a position of the cutter relative to the die.
However, when a gear mechanism such as the spinning disc and the nut disc is provided on the cutter shaft on the side of the die relative to the sleeve, the cutter shaft is elongated in the axial direction, and a housing for accommodating this cutter shaft is also elongated in the axial direction. Therefore, in the resin granulating apparatus of the patent publication above which needs large space for installation, there is a problem that the installation is difficult in a case of limited installation space.
When the cutter shaft is elongated on the side of the relative to the sleeve, the cutter shaft is naturally easily bent and curved. The cutter is attached to a front end of the cutter shaft so that a blade edge is perpendicular to the axial direction. When the cutter shaft is bent, there is a fear that the direction of the cutter is inclined so that the cutter is not easily in contact with the die surface. As a result, it is not possible to cut the resin while pressing the cutter onto the die surface without any gap therebetween, and thus there is a fear that a pellet of a good shape is not obtained.
Further, there is a demand for additionally providing the stopper means as in the patent publication above in the conventional resin granulating apparatus. However, the cutter shaft of the conventional resin granulating apparatus having no stopper means often does not have enough length for additionally installing the gear mechanism described above. For additionally installing such stopper means, there is a need for replacing all the cutter shaft, the housing and the like. In consideration with the installation space and stable supply of the pellet of the good shape, there may be some barriers in application to the existing facilities.